This invention relates to clutch hubs for use in transmissions of automotive vehicles, and more particularly to a clutch hub suitable for use in transmissions of the synchromesh type or constant mesh type.
Synchromesh transmissions are widely used in modern automotive vehicles. The transmission of this type is provided with a synchronizing mechanism which facilitates engagement of a slidable sleeve rotating coaxially on and with a shaft to be meshed with a gear of another speed in response to manipulation of the change lever. This synchronizing mechanism acts to bring the sleeve toward the gear so that the force of friction produced therebetween can be utilized to make the circumferential speed of the sleeve equal to that of the gear for facilitating the meshing engagement between the two gears. In a Borg-Warner type synchromesh transmission, for example, this synchronizing mechanism is composed of a splined clutch hub adapted for unitary rotation with an output shaft, a synchronizer ring mounted loosely on a conical portion of a driven gear, and spline hub sleeve for the purpose of engaging with gear splines, synchronizer ring and clutch hub. The clutch hub used in the transmission of this type has heretofore been manufactured by forging, sintering or the like due to the complex structure thereof. However, the manufacture of the clutch hub by the process above described has required a great number of manufacturing steps in addition to high material costs. Thus, the clutch hub manufactured by the prior art process has been quite expensive.
Further, the synchromesh transmission of the construction above described has not been satisfactorily reliable from the viewpoint of safety in that accidental self-disengagement of the hub sleeve from the gear splines tends to occur while the vehicle is running. In an effort to prevent occurrence of such an accidental gear self-disengagement, various clutch hubs and hub sleeves having splines provided with complex chamfered faces or circumferential groove have been proposed hitherto. However, these clutch hubs and hub sleeves have also been defective in that a complicated working process is required in addition to the difficulty of manufacture.